[rEvo] Petrel 2 controller intermittently shows 0.0/low PPO2 for all sensors

[mr_v]

When I start replacing pins (this week, whenever the pins show up), I will know how far the water has traveled up the wire.

I will cut the current pins off at the connector, then strip the right length of wire. If it's corroded, I will cut more off and repeat until I have good, clean, bare copper to attach the pin to.

If the wire gets too short, I really don't think it's a problem to splice on an extension with waterproof heatshrink over it. Test it by checking mV on a cell on a known good connector and then check it on a repaired connector to ensure it gives the same reading.

I'm not recommending that you or anyone else do that. You and everyone else should definitely buy a new part when the existing one gets corroded and is no longer reliable. That is surely the safest way to deal with it and what I would recommend to anyone to do.

I followed the advice today. As I had installed a new piggy tail wire, I dissected the old one to see what was going on.

Here is the picture of the wire ends that I cut off ~1/2" from the Molex connector. There is no "copper" color and lots of black residue.

After we exchanged text messages, I continued to dissect the wire and removed ~1" isolation at the time. In my case, the wire was quite done - moisture traveled almost to the "fused" or "potted" connection that linked the cells with the 4-PIN female outlet. At this point, I call it toast. Screwing with it is not worth it for me. I really wish this were a $20 part so that I could replace it yearly. A better design could help, too ;-(

 

[mr_v]

Isn't much. You can see the sealed molex connections and the piece of wrist seal the back end of the sensors rests on.View attachment 815914

Have you tried Molex covers like these:

Rubber Sensor Cover - Fits Molex Sensors

.

www.narkedat90.com

 

[Wibble]

I store my Revo in the garage open with the cover off, the scrubber canisters in Tupperware tubs and the cell tray out of the unit so the cells and lungs can breathe and dry out.

Thought about using the Narked cell caps but would imagine that they would just keep any moisture in the cell connector area and not clear to evaporate.

Really like the idea of injecting some Tribolube into the molex connector. Fluids don’t compress.

 

[mr_v]

I store my Revo in the garage open with the cover off, the scrubber canisters in Tupperware tubs and the cell tray out of the unit so the cells and lungs can breathe and dry out.

Thought about using the Narked cell caps but would imagine that they would just keep any moisture in the cell connector area and not clear to evaporate.

Really like the idea of injecting some Tribolube into the molex connector. Fluids don’t compress.

What are the long lasting effects of Tribolube? How do you clean it out if needed?

 

[stuartv]

@mr_v : Cool that you dissected it and saw for yourself that it was really dead. You have closure now.

It does suck that that part costs $100 and only lasted you, what 20 months or something like that? I think if you start filling those connectors with Tribolube, it will last longer in the future. But, when one sensor is $85 and you replace those annually, I don't think an extra $100 every couple of years for that cable part is like a dealbreaker on owning a rEvo. It's just one more peck from the duck. LOL

I think those Molex connector caps are intended to be put on the wires behind the molex connector. You connect the Molex to the sensor and then slide the cap down and over the sensor opening, to keep moisture from getting in there.

It's an interesting idea. I wonder how much difference that makes versus using nothing and versus filling the Molex with Tribolube.

If you order some of those caps, you can put me down for 5 and I'll split the shipping with you.

The long-term outlook on Tribolube seems completely solid, to me. When I took all my Molex apart on Sunday, the Tribolube was still in there and white. Maybe not as much of it there, as I've changed sensors a few times in the 3 or 4 (??) years since I squirted that Tribolube in there.

I don't know of any downside to having the Tribolube in there. If I wanted to clean it out, I would remove the pins from the connector and clean it all up any way you like. Wipe it off the pins. Maybe blow compressed air through the empty Molex? Or hot water?

 

[Wibble]

Issue with the cap is that the cavity is full of gas which will expand/contract with the ambient pressure. As the cells are actually within the loop, this means the breathing gas is very moist -- as can be clearly seen when opening the back and water literally runs out.

Once opened, the moisture will remain within the cell cap a lot longer than if the cell was left in the open.

Maybe those caps could be filled with silicone grease Tribolube (Tribolube's way too expensive!), injected by a syringe to fill the cavity?


Better still, it would have been a lot better if Revo had used potted coaxial connectors like the JJ.

*** edit: silicone grease in high PPO2 not a good idea.

 

[stuartv]

Issue with the cap is that the cavity is full of gas which will expand/contract with the ambient pressure. As the cells are actually within the loop, this means the breathing gas is very moist -- as can be clearly seen when opening the back and water literally runs out.

Once opened, the moisture will remain within the cell cap a lot longer than if the cell was left in the open.

Maybe those caps could be filled with silicone grease (Tribolube's way too expensive!), injected by a syringe to fill the cavity?


Better still, it would have been a lot better if Revo had used potted coaxial connectors like the JJ.

I'm not sure about using silicone grease in there, as it would be exposed to very high pO2s.

Tribolube is certainly not cheap. But, if you're as worried about all this as @mr_v is, then it seems like a small price to pay. I mean, spend $20 on Tribolube to fill them all and then never have to replace that wiring harness or any pins or Molex connectors? Maybe worth it versus buying a $100 wiring harness every couple of years....?

I think we should refer to this as the Atomic Aquatics Mod to R22D sensors... LOL

 

[stuartv]

Better still, it would have been a lot better if Revo had used potted coaxial connectors like the JJ.

I do like that the sensors rEvo uses are fairly ubiquitous. Probably the easiest to get, as so many CCRs use the same sensors. And I can use the same sensor in my Divesoft analyzer, when it's no longer good enough in my CCR.

And these wiring issues are cheap and easy enough to fix. Not sure how that compares to fixing a coax connector. I mean, those may last longer, but surely they too can get corroded and need to be replaced?

 

[Capt Jim Wyatt]

Silicone lube is not O2 compatible and should not be exposed to high PO2s such as would be seen in the head of a CCR.

 

[mr_v]

I agree with @stuartv - our sensors are pretty cheap and the overall fix cost, $100 in my case, was a rounding error compared to the total CCR costs.

Perhaps there is an intermediate solution. Molex connectors and wiring are quite cheap. So put a moisture resistant connector between a molex connector and the potted part of the piggy tail:

If moisture gets into the wire, it will travel up to the connector. Then replace the molex/connector part for less than 0.50 USD.